The present invention relates to an ink jet printer which sprays ink through the nozzle onto a paper for printing according to printing signals, or more specifically to an ink jet printer which is equipped with a cap for covering the nozzle face to prevent the nozzle from clogging, the cap being filled with maintenance solution to protect ink in the nozzle from drying and solidifying.
The ink spray nozzle of an ink jet printer is exposed to the atmosphere when the printer is not used. Ink contained in the nozzle therefore dries and solidifies, causing the nozzle to clog. Dryness and solidification of ink can also occur while the printer is transported or stored.
To prevent clogging, the conventional ink jet printer is equipped with a cap member for tightly covering the nozzle face while the printer is turned off or long out of service with power on so that ink in the nozzle may not be dried and solidified.
In the U.S. patent application Ser. No. 849, 791 filed on Apr. 9, 1986 and in the W. German patent application No. P3612299.8 filed on Apr. 11, 1986, the applicant has proposed an ink jet printer in which the cap member is filled with maintenance solution composed of solvent such an antimold agent or water so that ink in the nozzle does not dry and solidify when the printer is long out of service. According to this proposed application, the maintenance solution in the cap member is collected in a waste tank when a printing operation is started. The waste tank contains a water-absorbing polymer which absorbs the collected maintenance solution to become a gel.
FIG. 11 shows the proposed conventional device. As shown, a tank 128 has a waste collecting port 128A in the top wall and a joint port 128B in a side wall for supplying maintenance solution from a maintenance solution tank 126.
The maintenance solution tank 126 installed in the tank 128 comprises a flexible bag made by blow-molding resin material. The bag has an opening which is closed by a seal rubber 135. The rubber seal 135 is positioned in the joint port 128B.
The space surrounding the maintenance solution tank 126 in the tank 128 serves as a waste collecting section 127. A water-absorbing polymer 136 is placed on the bottom of the waste collecting section 127.
The water-absorbing polymer 136 ("SUPER LOVE" by Asahi Chemical Industry Co., Ltd. may be used.) is capable of absorbing 70cc of electrolyte for each 1 gram of the polymer. If liquid to be absorbed is pure water, the polymer 136 is capable of absorbing it by 700 to 1000 times the weight of the polymer. Absorbing the liquid, the polymer 136 becomes a gel.
However, since the water-absorbing polymer 136 itself is large in volume, it occupies a large space in the tank, leaving a smaller space for waste liquid. Therefore, it is necessary to replace the waste tank 128 frequently.